1. Field of the Invention
The present invention relates to an apparatus for insertion of an object into a close clearance hole. Specifically, the invention relates to such apparatus utilizing a double taper starter system wherein a first taper is provided to align the part radially and a second taper is provided to align the part angularly. Apparatus in accordance with the present invention includes a first taper; a narrow section of length such that with the part tilted to the angle of the first taper, clearance in the hole is maintained;, a cut-back segment of either constant diameter or reverse taper geometry; and a second taper of approximately the same size and shape as the first taper. The apparatus of the present invention can be advantageously used in mechanized assembly processes, the assembly of shafts into bearings, and in thermally assembled or regular interference fits.
2. Description of the Relevant Art
Assembly of objects into mating holes can be quite difficult, especially when the ratio of part diameter to part diametrical clearance within the hole is greater than about 500 to 1. Until the insertion has proceeded to a significant fraction of the diameter, these close fits are subject to jamming due to misalignment. Such jamming can result in gouging and scraping the surfaces of the parts. If the parts are massive, a jammed part can be difficult to remove. Delicate bearing materials and thin surface coatings are quite susceptible to assembly damage. In applications where rapid assembly is required, such as in thermal shrink fits or interference fits and automated assembly processes, jamming of close clearance fits can be a catastrophic problem.
Perhaps the most common solution used for this problem is a single taper on either member. Although a single taper solves the radial alignment problem, once the assembly is inserted past the tapered portion the angular alignment problem is similar to an assembly with no taper. Even where both members arm tapered, the problem still exists. While it is noted that long, very shallow single tapers can decrease the frequency and severity of jamming, the excessive starter section lengths required are not acceptable for many practical applications.
Attempts by others to provide apparatus for insertion of an object into a close clearance hole have failed to provide a design suitable for use where the ratio of part diameter to part diametraly clearance within the hole is high or where it is desired to quickly assemble the parts or protect a surface coating. Accordingly, it is therefore desirable to provide an apparatus which allows the assembly of objects in a close clearance hole which can be used in rapid assembly and which minimizes the frequency and severity of jamming when parts are assembled.